Slack adjuster



Feb. '5; 1929.

C. C. FARMER` SLACK ADJUSTER Filed Jan. 1'7, 1927 INV E NT OR cum: crAnMER Illllllllll Til/lll,

ATTORNEY Patented Feb. 5, i929.

CAYDE C. FARMER, rOF PTTSBRGH, PENNSYLVANIA, ASSIGNOR TO THE ser . TION OIF FENNSYLVANIAA.

' SLACK '.ADJUSTER.

Application filed January 17, 1927. Serial No. 161,485.

This invention relates to slack adjusters as employed with air brake equipment on railway cars, and more particularly-to slack adjusters ot the pawl and ratchet bar type. h

The principal object of my invention is to provide an improved slack adjuster of the above type. f

ln the accompanyingjdrawing: F ig. 1 is a view in elevation illustrating the manner in which my slack adjuster is applied to a freight car; F ig. 2 an enlarged view, partly in section, otl -theslack adjuster shown in Fig. 1 5 and Fig. 3 a section on the line 3-3 of Fig. 2.

As shown in the drawing, theslacl adjuster comprises a cylindrica'lcasing a, secured to the side of the truck bolster or cross member 5 by two brackets 6 and 7. Numeral 3 designates the cross member of the car body (not shown) corresponding to the truck bolster 5, while the distance between said members illustrates the limited clearance generally found in car construction.

The cylindrical casing t'of the slack ady juster is formed in two portions, 9 and 10,

having bolting flanges by which they are secured to each other by cap screws 11.

Mounted in the casing i is a ratchet bar 13, the outer end of .which extends through i an opening in the portion9. A lug 11il 1s' formed integral with said casino' 'and is adapted to carry a holding pawl 15, pivoted on the pin 16, said pawl having -a point-` ed end adapted to engage the teeth 18 on the upper side of the ratchet bar 13 and passing through anopening 17 in the casing.

ln the portion 10 of the casing is a hollow sleeverl9 adapted to extend through an opening 20 in the outer end ot said portion and having at the outer end an apertured lug 21, disposed outside of said casing. Secured at the opposite end of said sleeve is a collar 22 and interposed between said collar and the casing wall 23 is a coil compression spring 24, adapted to normally hold said collar and sleeve in the position shown in the drawing.

The sleeve collar 22 has a lug 25 eX- tending upwardly through a longitudinal slot 26 in the casing, said lug being adapted to carry a take-up pawl 27 pivoted 'on the pin 28, said pawl having a pointed end adapted to engage the teeth 18 on the upper side of the ratchet bar 13, and extending through a slot 29 in the portion 9 of the casing, which slot is in alinement with the slot 26 in the portion 10.

A pin-30 is laterally secured to the hol-ding pawl 27 and .is adapted to operate on 1nclined cam shoulders 31 formed on the walls, adjacent the slot 29. f y

The ratchet bar 13 extends hollow sleeve 19 and near its longitudinal center is provided a laterally extending pin adapted to operate in'a longitudinal slot 33 formed 1n the portion 9 of the casing. The outer end of said pin 32 is pivotally securedy to one end of a link 35, the other endy ot' said linlr being securedto the usual dead truck lever 3e on the,y car truck.

The aperture ofthe lug 21 `of thesleeve 19 is adapted to receive one end of al chain 36, the opposite end of the chain being fastened to one end of the usual live truck lever 37. also secured to the saine end-of the live lever is theA usual pull rod (not'shown). Y

rlie dead lever 34 andl live lever 37 are tied togetherby acompression yrod 38 andl each lever is adapted to be secured to the usual t'ruclr member, carrying the brake shoes, at the movable iculcrum spectively.

In operation, when the brakes on a car are. applied, the vupper end of thelivelever 37 moves tothe right due to the pulling vtorce of the pull rodlnot shown). Said lever-being connected to the dead lever 34' licient to cause the chain 36 to pull and move the sleeve 19 and the take-up pawl 27. The direction of pull oia the dead lever 34 on the ratchet bar 13 is such as to tendv to shift the bar to the' right, but the engagement of the holding pawl 15 in the teeth 18 of said bar prevents such movement. f v

It the brake cylinder piston travel on' the car should exceed a predeterminedamount, the chain 36, connected to the live lever 37, is pulled toward the right, and thereby moves through the points 39 and 40, rer

wnsriNe-l the sleeve 19 outwardly against the pressure wardly, said pawl riding out ot' engagement with the teeth 18 of the ratchet bar 13, with which it was engaged. Il thepawl 27 moves a greater distance than that which separates two adjacent teeth on the ratchet bar 13, the pin 30 rides up onthe inclined cam shoulders 31 and along the top of the slot in the casino. During this action, the ratchet bar 131s held against movement to the right by engagement ot the holding pawl 15.

When the brakes are released and the upper end ofthe live lever 3T returns to its'noi'- mal position to the left, the pressure ot spring 2li forces the sleeve 19 inwardly. The takeup pawl 27, moving with said sleeve, engages' the ratchet bar one tooth to the right ot the tooth it had previously engaged on said bar and this results in the spring 24 shitting the ratchet bar 13 to the lettv a distance equal to one tooth. The holding pawl 175 does not interfere with movement ot the ratchet bar to the left, sol that as said bar is shifted the distance of one.'v tooth, the holding paivl l5 rides out of engagement with thetooth it had been previously engaged with and drops into engagement. with the next tooth to the right. lnthis manner, excess piston travel is takenup step by step and thus the piston travel is held within narrow limits.

The relative horizontal positions ot the slack adjuster ratchet pin 32 and the hori- Zontally movable ulcrum point 39 o'l' the dead lever 3l are tix-ed, so that as the deadV lever 34 revolves about the fulcrum 39, when the ratchet bar 13 moves to the lett in taking up slack, the upper end of the dead lever is subject to a vertical movement. The link connection35; provides a flexible connection between the upper end. ofv said lever and the x'edratchetrpin 32, however,.to permit said vertical movement without affecting their horizontal relation.

The laterally extending ratchet pin 32 in being centrally located on the ratchet bar 13 prevents vertical thrust of the ratchet bar in the casing when applying the brakes, and a consequent tendency ot' vertical wear ot the casing, which might result Ain inaccurate alinement ot the engaging pawls.

By securing the slack adjuster to the side of the truck bolster or cross member 5, by

necessary to provide space sufficient for the chain 36 and it necessary the construction ot the device can be such that the chain may be device, since with this construction, it is only operated through a suitable opening in the cross member 5.

Having now described my invention, what l claim as new and desire to'secureby Letters Patent, is

1. The combination with a live lever and a dead lever, of an automatic slack adjuster comprising a ratchet bar, a link operatively connecting one end ot said dead lever tov said ratchet bar at a point on the ratchet bar sub stantially midway between the ends, and

means for ad'ustin` said ratchet bar to take I upA slack.

2. rlhe combination with a live lever and av dead lever, ot an automatic slack adjuster comprising a ratchet bar operatively connected at a point intermediateV its ends with one end of said dead lever, and means for adj Listing said bar to takeup slack.

3. rlhe combination with a livelever and a dead lever, ot an automatic slack adjuster comprisingV a ratchet bar having a pin intermediate its ends, a link connected at one end to said pin and havingthe other end 'connected to said deadlever, and means tor adjusting said bar to take up slack.

In testimony whereof l have hereunto set my hand. e Y

CLYDE C. FARMER. 

